Process of preserving food products.



J. M. YOUNG. PROCESS OF PRESERVING FOOD PRODUCTS.

APPLICATION FILED MAR. 1. I912.

Patented Apr. 4, 1916.

UNITED s'raras Parana carton.

a JOHN MARSHALL voune, or SAN rnnncrsco, carrromrm, assrenoa 'ro amaaican CAN GOMPANSLDF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

PROCESS OF PRESERVING' F601) PRODUCTS.

fiancee Specification of Letters Patent.

Patented Apr. a, rare.

Applicationfiled March 1, 1912. Serial no. 680,927.-

I To aZZ whom it may concern Be it known that I, JoHN MARSHALL YOUNG, a, citizen of the United States, residing in San Francisco, in the county of San Francisco and State of California, have invented a new and useful Improvement in Processes of Preserving Food Products, of which the following is a specification.

This invention relates to a process of preserving food products and more particularly to theirpreservation in hermetically sealed open-top sheet-metal cans.

The invention consists in the met of procedure hereinafter fully explained and claimed.

In the accompanying drawing which forms a part of this specification Figure 1 is a diagrammatic representation of the process. Figs. 2, 3, 4: and 5 are sectional views "of a can of food to illustrate the several steps.

In recent years many of the packers of food products have preferred to use what is known in the trade as the sanitary can, that is to say a can the entire top of which is open to receive the contents, and to be closed by covering with a one-piece sheet metal cover, such can and cover being interfolded or seamed together. Formerly the general practice was to use cans with the cover having a stud hole of lesser diameter, to be in turn capped with a small diameter soldered cap, the final closure being by means of a drop of solder applied to a vent hole in such cap. With these stud hole cans and vented caps very little 'difliculty was experienced in a suitable final hermeti- "cal closure; but when the sanitary or open top can with its many other advantages was adopted great difficulty was encountered in the proper final hermetical closing of the can. To overcome these difficulties the present process was devised.

One of the most serious troubles encoun- Eered by the packers in the final closing of he filled sanitary or open-top cans was the procuring of a proper amount or degree of vacuum or diminished tension in the filled can when finally hermetically sealed. As is well known when the contents of a hermetically sealed package begin to spoil this fact is indicated to the observer by the swelling of the can and outcurving of the flat ends. Such cans are called swell heads and are usually considered a loss. It frequently happens, however, that packages of which the contents are perfectly good and unspolled assume the appearance of swell head cans because of the generation of harmless gases in the interior of the package not at' all due to fermentation or spoiling but due only, for example to the action of acids in the foods upon the tin or upon the other contents of the can in the presencebf air in the package. Such generation of gases, unlike that produced by fermentation is limited in amount and not progressive, but, still, is often suflicient t0 produce the swellhead appearance and thus to give a false indication of spoiled contents; and since this false indication'cannot be ignored nor its cause and falsity determined without opening the'can it may and often does result in a loss of both can and contents.

The present invention provides a remedy for this accidental creation of false swell heads in sanitary cans as follows: I fill the swell head appearance which appearance is thus not produced unless the progressive and continued generation of gases occurs such as accompanies the spoiling of the contents. be left in the filling of the can may be con-- The amount of vacant space thus to siderably varied even in cans' of the same size. I find that with-an ordinary salmon can one and one-half to two cubic inches will be suflicient; this space should not be filled with'water or liquid but left vacant or occupied only by air. In the old process the blowing off of the vent in the exhausting operation especially where the contents of the can were partly liquid would automatically produce a considerable vacancy by discharging vapor and liquid from the can lIL 'a' sudden violent manner, although the action was not always certain, but in the closing of the sanitary cans such puncture, venting, and subsequent soldering, are not deemed desirable and I therefore leave the vacant space originally in the can instead of seeking to subsequently produce it by a purging or venting action. A vacancy equaling in-volume from three to six per cent. of the cubical contents of the can will ordinarily be suflicient. When the cans are thus partially filled they are to be placed in the exhaust chamber and subjected in the usual way to the action of live steam forced against the cold exterior of the can to heat up the can and. its contents to cause the gaseous contents of the can to greatly expand. And that the condensing of the live steam by contact with the cold can and food shall not operate to fill or partially fill with water the vacancy thus purposely left in the can, I loosely apply the covers to the cans in such manner that they shall be held in place leaving the joint between the cover and the can sufliciently open to permit the escape of the expanded air from the prearranged vacancy and whatever vapors are generated within the can by the heating. lVhen the contents thus shielded and in closed by the cover are heated, and the gaseous and vaporous portion is thus driven out to produce the attenuated condition of the air the cover and can are then joined together by further interfolding or sealing and'a hermetical joint produced in some suitable manner between the cover and the can, which may be done by simplv interfolding and compressing the parts of said cover and can with or without an interposed packing, or, if that be preferred, by soldering the seam between cover and can, although one of the purposes of the use of the sanitary can would of course be defeated by the employment of soldering in this relation. A final prolonged heating of the sealed can and contents is required or advantageous with some kinds of food products. as is well known, and where required I do this to save heat preferablv immediately after the above hermetical sealing.

In the practice of this process I proceed as follows: I use the ordinary open-top sheet-metal can such for example as is shown in Figs. 2, 3, 4 and 5 of the drawing. The can body is indicated in said drawing at A; the'bottom head is shown at B, the top head or cover at C. The can body at its upper edge is flanged as at a and the cover furnished with the flange cl having the incurved outer edge e and preferably provided with the inclosed packing material f. G represents the contents, and H the purposely left vacancy in the can. This vacancy is intentionally somewhat exaggerated in the drawing for purpose of illustration. The can partially filled is next supplied with the cover C and placed in a machine or mechanism J in which a roller is made to operate upon the joint between cover and can and to cause the cover flange to be folded or tucked under the can body flangeas for example in the manner shown in Fig. 3. This interfolding is preferably done around theentire circumference of the can. The can is now in condition to be placed in the live steam chamber K where it is subjected to the action of jets 7c of live steam that impinge upon the exterior of the can and its cover. Much of this steam is of course condensed by contact with the cold can, but the cover shields the contents of the can so that the water of condenstion does not "penetrate to the interior and thus does not tend to fill and destroy the vacuum vacancy. The can and contents are heated by the impinging steam to any degree desired, depending somewhat upon the nature of the food product preserved, and this heating is kept up until the gaseous contents of the can are in a state of considerable expansion. When the air, and whatever vapor is generated by the heat, expand, they forcethemselves out through the loose joint between the can and cover until the tension or pressure within the can equals the atmospheric pressure outside. And this equilibrium is maintained so long as the heat continues. It will be readily understood that this exhausting of the gases and vapors under tension prepares the can for the creation of a partial vacuum therein, quite as efliciently as though the can had been sealed, vented by a puncture, purged of its expanded gases and a portion of its contents. and with the advantage that the puncturing. purging and subsequent closing of the vent by soldering are avoided. While the loosely. covered can is subjected to the heating action of steam as above and its contents are expanded. the tendency will be to swell the cover at top and bottom outward as indicated at Fig. 4, the amount of such swelling depending upon the tightness which the expanded gases escape through the joint. After the gaseous contents of the can are thus exhausted in the present process, the joint between the body and cover is completed in a suitable seaming machine L which mav produce a seam similar to that indicated in said Fig. 52 And now as the contents of the can cool its gaseous contents shrink bv loss of tension and the heads curve inward as indicated in said Fig. 5. Subsequently in case of the generation of harmless gases. not due to spoiling or fermentation and therefore of limited amount. these harmless limited gases simply act to flow into the partial vacuum in the can, where they slightly increase the tension and sometimes. lessen the curvature but never amount to enough to produce the vicious false swell-head appearance which this process is intended to obviate. After the double seaming or hermeticalclosure above described the cans may be further of the joint and the relative freedom with subjected to prolonged heat for the purpose of destroying high resistance germs if any by placing said cans and their contents in the usual heating chamber N.

I claim:

1. The process of preserving food, consisting in placing the food in a can; leaving in said can an unfilled space suiiicient when exhausted of a portion of its air to contain any gases that may be generated by the chemical action of the contents other than gases due to progressive spoiling; applying the cover to the can loosely; partially exhausting by means of heat the air from the can through the loose cover joint, so as to produce a partial vacuum Within the can; and While such partial vacuum exists, hermetically closing the seam between the can. and the cover,

2. The process of preserving food, consisting in placing the food in a can; leaving in said can an unfilled space sufficient when exhausted that a portion of its air to contain any gases that may be generated by the chemical action of the contents other than gases due to progressive spoiling; applying the cover to the can loosely and securing the cover against upward pressure of solid contents; partially exhausting by means of heat the air from the can through the loose cover joint, so as to produce a partial vacuum Within the can; and While such partial Vacuum exists, hermetically closing the seam between the can and cover.

eons nansnann tonne;

Witnesses:

(It A. Eocene, B. MARSHALL, A. I. ATHEARN. 

